What is a cipher? According to Wikipedia (1), it is an algorithm for performing

encryption or decryption -- a series of well-deﬁned steps that can be followed as a

procedure. Another way to think about this is that it is a process of taking text

through steps to change it. Also, when working with symmetric ciphers, the inverse

of the process will convert the message back to the original text. Below are the

characteristics of the three symmetric encryption ciphers up for discussion.

Character

o Substitution or shifting is done one character at a time

o ROT13, also known as the Caesar Cipher, is my favourite one which shifts

13 characters to the right on the alphabet (2)

o The simplest of the three

o Only use this cipher when learning or the con#dentiality and integrity is

not essential as it is the easiest to defeat

Block (3)

o The input text is encrypted in chunks of #xed size

o More computationally intensive than Stream

o Use this cipher for data at rest

Stream (3)

o Faster than Block

o Encrypted one bit at a time

o Use this cipher for data in transit

Challenge for my classmates, can you decrypt this?

jrrx 6 vf n terng fhowrpg

Sources:

1. No author.No date.Cipher.p. 1.https://en.wikipedia.org/wiki/Cipher.

2. No author.No date.ROT13 Cipher.p.

1.http://practicalcryptography.com/ciphers/rot13-cipher/.

3. Casey Crane.January14,2021.Block Cipher vs Stream Cipher: What They Are

& How They Work.p. 1.https://www.thesslstore.com/blog/block-cipher-vs-stream-

cipher/.